Recently, a non-contact charging method in which magnetic field resonance and electric field resonance are used has attracted a lot of attention as a non-contact charging method for a strongly coupled system using resonance. For example, the method is expected to be utilized for charging an electric device etc. However, since a power transmitting device transmits specified electric power in the conventional non-contact charging method, such a equipment device is unable to supply necessary charging power simultaneously to equipment devices having respective power receiving devices, each of which requires different power (charging power). This is, because the distribution ratio of the charging power to each of the equipment devices is determined depending on the coupling state of transmitting and receiving devices, and does not always match necessary electric power. That is, in the case in which a power transmitting device and a power receiving device are the same coupling state (for example, the equipment devices are equally located in distance), the power (transmitting power) transmitted from the power transmitting device is equally supplied to a plurality of equipment devices. Therefore, when the equally supplied electric power is larger than the charging power of the equipment devices, overcharge is incurred. Furthermore, when the equally supplied electric power is smaller than the charging power of the equipment devices, undercharge is incurred. Therefore, the equipment devices which expect a plurality of different values of charging power are not simultaneously charged.
For example, disclosed as a related technology is a charging system which simultaneously and equally charges a plurality of sensing devices. The charging system includes: a plurality of sensing devices which receive electromagnetic waves and charge the electric power obtained from the energy of the electromagnetic waves; a housing unit which stores a liquid in a concave portion; a radio wave emission unit which emits electromagnetic waves in the concave portion, and a stirring unit which stirs in the concave portion the liquid stored in the concave portion. Each sensing device charges the electric power obtained by receiving electromagnetic waves mixed in the liquid stored in the concave portion, moving in the concave portion depending on the stirring operation of the stirring unit, and emitted from the radio wave emission unit.
Also disclosed as a related technology is a positioning device for a searching system which may serve for a long period by providing a charging circuit which charges a battery by receiving electromagnetic waves, obtaining electric power which may be transmitted far. The positioning device for a searching system includes: an antenna which receives electromagnetic waves; a charging circuit which charge a battery with the electric energy of the received electromagnetic waves; a receiver which receives a call signal; a transmitter which is driven by a battery; and a storage device. The storage device stores owner identification information for identification of the owner of an equipment device. The receiver receives a call signal including the owner identification information, activates the transmitter when the battery is charged, and transmits to the transmitter a signal including the owner identification information stored in the storage device. For example, refer to the patent documents 1 and 2.
Patent Document 1: Japanese Laid-open Patent Publication No. 2009-253997
Patent Document 2: Japanese Laid-open Patent Publication No. 2005-229150